1. Field of the Invention
The present invention relates to a printing apparatus including a printhead having a power storage unit, a charge control method and a storage medium storing program thereof.
2. Description of the Related Art
Inkjet printing apparatuses including an electric double-layer capacitor (EDLC) are conventionally known (Japanese Patent Laid-Open No. 11-320928). The EDLC is mounted in, for example, the carriage of an inkjet printing apparatus, and is used as a power source for driving a heater. With this configuration, the need to provide a power supply wire between the main body of the inkjet printing apparatus and the printhead can be eliminated. Furthermore, by configuring the inkjet printing apparatus so as to be capable of transmission and reception of print data and the like through wireless communication using, for example, infrared rays, the need to provide a flexible cable can also be eliminated.
With this configuration, in order to prevent printing from being interrupted, the EDLC is required to have a power storage capacity in such an amount that at least a single page's worth of data can be printed on the printing medium. This is because if an interruption occurs during printing of a page due to recovery processing or the like, the temperature of the printhead drops rapidly during the interruption, resulting in a change in printing density. Such a phenomenon appears pronouncedly in high duty images. Accordingly, the EDLC needs to have a minimum electric power capacity required to print at least a single page's worth of high duty image data. However, such an electric power capacity is relatively large, and as a result, the charging time of the EDLC increases. Also, particularly when continuous page printing is performed, a long standby time is required during printing.
Japanese Patent Laid-Open No. 2009-535007 discloses a configuration in which a high-capacity EDLC is newly provided so as to directly charge a low-capacity EDLC. In such a configuration, when the high-capacity EDLC that has been fully charged and the low-capacity EDLC that has been completely discharged are connected in parallel, a current flows such that the voltages of these EDLCs are uniform. EDLCs have a low equivalent series resistance, and thus charging can be finished in about several to several ten seconds.
In the case where an inkjet printing apparatus in which such a high-capacity EDLC is mounted is unpacked or is left for a long period of time with its power cord plug being unplugged from a power outlet, the high-capacity EDLC needs to be charged. However, it requires a longer charging time than the above-described EDLC that is mounted in the carriage, and as a result, the standby time increases.